A federal grand jury has indicted a local couple on a felony charges of conspiracy to commit arson related to the fire that heavily damaged their business, Ed Davis Autos & RVs in Fair Haven.

The federal conspiracy charges, which were filed last week, come about a month after the state dismissed charges of arson against Edward Davis, 50, and his wife, Tammy Davis, 46.

The charges say the pair “knowingly and willfully conspired to maliciously damage and destroy, by means of fire,” their Washington Street business March 17, 2013.

The Davises are scheduled to be arraigned on the federal charges at 1:30 p.m. Monday in Burlington before Judge John M. Conroy.

In the original state charges, investigators said the cause of the fire was related to an acetylene/oxygen welder, which was found with its valves open near some tires.

The investigation showed the Davises were more than $1.1 million in debt and owed more than $7,000 in property taxes to the town of Castleton and $21,000 in property taxes to the town of Fair Haven.

David Silver, attorney for Tammy Davis, said the pair have been defending themselves for more than a year.

“How awful it is to be charged with serious arson charges and go through almost a year of litigation,” Silver said. “(The Davises) used all their resources to defend themselves. We thought the state case was falling apart and then at the end of the discovery process, as we were getting ready to depose the lead arson investigators, the state decides to dismiss and give the case over to (federal prosecutors).”

Silver said his client is innocent and that makes it even worse.

“You can imagine how awful that is for an innocent person,” Silver said. “I’m confident the evidence is going to show that.”

Attorney Dan Davis, no relation, represented Edward Davis in the state case, but no determination has been made as to who will handle his federal charges.

Dan Davis said that as he prepared to depose the state arson investigator on the state case, State’s Attorney Marc Brierre called to say they were dismissing the case.

Dan Davis said the federal charges do not require the arson investigators to be deposed.

“Keep in mind that when you have an arson case, you have to prove that it’s arson,” Dan Davis said. “That’s the proof that any prosecutor has to make.”

Silver is confident Tammy Davis will be exonerated.

“I’m asking everybody to keep an open mind,” Silver said. “This is an innocent person and we’re going to have our day in court.”